Image 1: A Pacific Giant Salamander (Dicamptodon tenebrosus), enjoys its lunch. Source: Industrius Info

Introduction

Since 1993, data on Pacific Giant Salamanders has been collected in/along Mack Creek, part of the H.J. Andrews Experimental Forest in Western Cascade Mountains of Oregon. This data collection is part of a larger effort, begun in 1987 to monitor local cutthroat trout populations (2). The H.J. Andrews Experimental Forest is a research site supported jointly by the University of Oregon and the U.S. Forest Service, and funded as part of the National Science Foundation’s Long-Term Ecological Research program (1). Data collection for Pacific Giant Salamanders occurs in two distinct areas, a coniferous old-growth forest and a clear-cut area (c. 1963) (2). Observations gathered pertaining to salamander abundance, weight, type, and location can provide insight as to how the species is affected by factors such as climate change, land use, and other disturbances over time (1).

Data and Methods

Image 2: Location overview of H.J. Andrews Experiment Forest Source: H.J. Andrews Experimental Forest

Image 3: H.J. Andrews Experiment Forest Source: H.J. Andrews Experimental Forest

Results

A: Visualizing salamander abundance between old growth and clear cut sections of Mack Creek

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Figure 1: Salamander abundance

B: Salamander counts by channel classification

Table 1: Salamander counts by channel classification. In 2017, the highest abundance of salamanders in both clear cut (CC) and old growth (OG) forests were found in cascades (67.1% and 62.8%, respectively), followed by side channels (24.5% and 23.1%), and then pools (8.4% and 14.1%).

Section Cascade Pool Side channel
Clear cut 247 (67.1%) 31 (8.4%) 90 (24.5%)
Old growth 201 (62.8%) 45 (14.1%) 74 (23.1%)

C: Impacts of forest condition of salamander location

In 2017, there is not a significant effect of forest condition (old growth/ clear cut) on where in the channel salamanders are found (cascade/pool/sidechannel) (\(\chi\)2(2) =5.54, p = 0.063)

D: Relationship between forest condition and mean salamander weights

Mean salamander weights did not differ significantly between clear cut and old growth forests [t(693)= 1.67, p= 0.096] The actual difference in mean values for clear cut and old growth forests is 1.19 grams. It should be noted that data for both locations are skewed, with distributions concentrated toward smaller weights.

E.

Summary

-In both clear cut and old growth forest, salamanders were found in the highest abundance in cascades, as opposed to side channels or pools.

-Forest condition does not have a significant effect on salamander location, nor does it have a significant effect of mean weights of salamander populations.

-Channel classification has a small but significant effect on mean salamander weights. (say something here about skewed data/means?)

References

“Aquatic Vertebrate Population Study in Mack Creek, Andrews Experimental Forest, 1987 to Present.” LTER Network Data Portal, portal.lternet.edu/nis/mapbrowse?packageid=knb-lter-and.4027.12.

“H.J. Andrews Experimental Forest - Oregon State University.” H.J. Andrews Experimental Forest - Oregon State University, andrewsforest.oregonstate.edu/.

“Pacific Giant Salamander Eating.” Industrious Info, www.industrious.info/55/08768-pacific-giant-salamander-eating.html.